Dear Purvi!

You can fill CLAT application form if have secured minimum 45% marks (40% for sc/st candidates) in class 12. There is no age limit. Ideally one should go for CLAT after class 12 for taking admission in 5 year Integrated LLB programme. As you are on the verge of completing your graduation you should go for 3 year LLB Programme and by doing this you'll save 2 precious years.

I hope it helps.